This section discusses background information useful to enable those skilled in the art to make and use the inventions of Applicants'. It is not an admission that any information herein is prior art or is analogous art or that a search adequate for examination, has been made.
Small credit card sized computer peripherals which plug into slots in a computer system have become very popular especially for portable computers. A specification by the Personal Computer Memory Card International Association (PCMCIA) for PC memory cards was released September 1991. The specification is available as issue PCMCIA PC Card Standard Release 2.0 from the association. The cards are required to be 85.6 mm long and 54.0 mm wide which is the same size as a standard credit card. Three types of cards are specified, all with the same length and width and same thickness of a card guide sections, but with different respective thicknesses of a thicker section of the card. The thicker sections of Type I cards are 3.3 mm thick, Type II cards are 5 mm thick, Type III cards are 10.5 mm thick. The specification includes minimum structural requirements for withstanding torque, bending, flexing, impact (drop), shock, vibration, warpage, moisture, and other mechanical requirements. The cards are also required to meet standards for withstanding EMI, RF, and ESD that are usually met by providing a metal cover. The cards are also required to meet other standards set by JEDIC, ISO and others. The specification also includes details of a 68 pin connector and slot size for the cards.
The cards are used for flash memory, networking, modem connections to telephone systems, hard drives, cellular telephone connection, sound cards, and I/O interface with other external peripherals. Although primarily used for laptop and palmtop systems, recently card slots have appeared in desktop systems.
U.S. Pat. No. 3,586,816 to Hagen, suggests laser focusing and optics for microscopic multiple spot welding.
U.S. Pat. No. 4,386,388 discloses a cover formed of sheet aluminum which is lap jointed and spot welded.
U.S. Pat. No. 4,833,295 to Locker suggests laser or electro beam welding of a lap joint.
U.S. Pat. No. 4,845,447 suggests tack welding a cover plate on a trap filter in a video cable distribution system.
U.S. Pat. No. 4,873,415 to Johnson suggests laser welding a lap joint to form a weld which is not continuous between galvanized steel sheets.
U.S. Pat. No. 5,302,801 to Kanda suggests using a oxygen-free atmosphere for laser welding leads of semiconductor devices to junctions on printed circuit boards and laser welding devices for such applications.
U.S. Pat. No. 5,107,073 to Steffen suggests ultrasonic welding between plastic surfaces to connect the upper and lower shells of a credit card sized cartridge containing fragile logic circuits.
U.S. Pat. No. 5,276,298 to Jones suggests using a Nd:YAG (yttrium aluminum garnet) laser to form overlapping spot welds to weld the metal edge of a lap joint.
U.S. Pat. No. 5,339,222 to Simmons et al suggests a metal, snap-together cover and dielectric frame for a PCMCIA card.
U.S. Pat. No. 5,354,964 to Kyoren suggests a source and apparatus to deliver inert gas such a argon to a high power CO.sub.2 or YAG laser welding site. He also suggests a lap weld joint between flat aluminum plates.
U.S. Pat. No. 5,397,857 to Farquhar suggests ultrasonically welding abutting surfaces of plastic frames to hold two stamped steel covers for a PCMCIA card. Resistance welding of metal butt joints is also disclosed.
"Credit Card Adaptor Cover Set" by M. J Lawrence, F. E. Morene and A. E. Ridley in IBM Technical Disclosure Bulletin Vol 37, No. 08, August 1994, p51, suggests a single piece cover for a PCMCIA card and providing a spring contact in the cover to touch grounding tabs on the electronic card assembly.
Continuous laser welds have been used to connect butt joints along three edges of stainless steel covers for PCMCIA cards. The butt welds are about at the midlevel of the edge walls of the cards. Accurate positioning of the butt edges of the seam for such welds is very difficult and costly to maintain and if not precisely maintained may result in the beam entering the card and damaging the contents.
Various metal snap together covers are available from A.K. Stamping company and other suppliers.